Hilchos Maasei Hakarbanos 2:14

The measurements of the libations listed in Sefer Yechezkel (the biblical Book of Ezekiel), the list of the offerings and the order of the service given there all refer to inauguration offerings (for the third Temple) and not what would be done in perpetuity after that. Rather, the prophet described what the inauguration offerings would be like when the altar of the rebuilt Temple is dedicated in the messianic era.

Hilchos Maasei Hakarbanos 2:15

This is just like when like the Tribal heads brought offerings when the altar of the Mishkan (Tabernacle) was dedicated (i.e., in the wilderness following the exodus); they brought offerings that would not be brought in subsequent generations, and such offerings were brought even on Shabbos. Similarly, a leader will bring a dedication offering on the future Shabbos, as described in Sefer Yechezkel (46:4). Similarly, the offerings of those who returned from exile in the days of Ezra were inauguration offerings that would not be brought in subsequent generations. The permanent practice is what’s described in the Torah as received via Moshe, to which we may not add and from which we may not subtract.